gpu: Implement idle async pixel transfers.

gpu/command_buffer/service/gles2_cmd_decoder.h

Index: gpu/command_buffer/service/gles2_cmd_decoder.h
diff --git a/gpu/command_buffer/service/gles2_cmd_decoder.h b/gpu/command_buffer/service/gles2_cmd_decoder.h
index 27fe96810d76627504d7a4cb66ca98cceb7fb30f..b7978756b2b076548b0316c56e776af398eed7b1 100644
--- a/gpu/command_buffer/service/gles2_cmd_decoder.h
+++ b/gpu/command_buffer/service/gles2_cmd_decoder.h
@@ -198,6 +198,11 @@ class GPU_EXPORT GLES2Decoder : public base::SupportsWeakPtr<GLES2Decoder>,
   // Process any pending queries. Returns false if there are no pending queries.
   virtual bool ProcessPendingQueries() = 0;
 
+  // Returns false if there are no idle work to be made.
+  virtual bool HasMoreIdleWork() = 0;
+
+  virtual void PerformIdleWork() = 0;
+
   // Sets a callback which is called when a glResizeCHROMIUM command
   // is processed.
   virtual void SetResizeCallback(